Some bacterial cells contain plasmids, small circular DNA molecules, in addition to the larger bacterial chromosome. Usually, plasmids are easily separated from chromosomal DNA in laboratory procedures.
The nucleotide content of chromosomal DNA is different from that of plasmid DNA.
Chromosomal DNA is enclosed within a phospholipid bilayer, while plasmid DNA is not.
Chromosomal DNA has some protein bound to it, while plasmid DNA has very little protein.
Plasmid DNA is less susceptible to a chelating agent.